The media is in the business of selling candy to the eyes and ears of consumers in the form of highlights and hyperbole. There simply aren't a lot of old Marino fans watching his show compared to the number of fans who are interested in the current players. There is always an obvious and severe bias towards current players as the greatest of all times, because hyperbole sells. When Favre played, he was half of what they talked about. Then he retired, and a few years later, he's just another good QB they seldom mention. Then it was all about Peyton. Now it's all about Brady.
Sure, MJD is going to over-hype the current players. Sure, he's going to extra-over-hype players he played with or has a good relationship with to get inside insight. His job depends upon two things ... how the current audience reacts to him, and his relationships with current players. So yeah, he's super-biased ... as most of them are. He's also not a guy who was raised or vetted as an announcer. He's a former-player who is adapting to being an announcer. His sounding board before were his teammates ... now it's the public, and he'll have to adjust his opinions and delivery.
But rest assured, none of the media has any interest in doing any sort of fair analysis between current and past players. It's about ratings ... not accuracy.